[Passwords] Add base::Feature for Additional Server Predictions

This change adds a new base::Feature to control processing of additional
server predictions during the form parsing stage. Populating these
additional fields is a recent server side change (http://cl/340884706)
only taking effect in Chrome M88+. This feature allows measuring the
impact of these new suggestions as part of a A/B experiment.

Bug: 1140493
Change-Id: I3741368e301c58c5adf7be21ac2947bf0d792e76
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2529552
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826247}

components/password_manager/core/browser/form_parsing/password_field_prediction.cc

@@ -4,9 +4,11 @@
 
 #include "components/password_manager/core/browser/form_parsing/password_field_prediction.h"
 
+#include "base/feature_list.h"
 #include "components/autofill/core/browser/form_structure.h"
 #include "components/autofill/core/common/form_data.h"
 #include "components/autofill/core/common/signatures.h"
+#include "components/password_manager/core/common/password_manager_features.h"
 
 using autofill::AutofillField;
 using autofill::FieldSignature;
@@ -18,22 +20,36 @@ namespace password_manager {
 
 namespace {
 
+bool AreSecondaryPredictionsEnabled() {
+  return base::FeatureList::IsEnabled(
+      features::kSecondaryServerFieldPredictions);
+}
+
 ServerFieldType GetServerType(const AutofillField& field) {
-  // The main server predictions is in |field.server_type()| but the server can
-  // send additional predictions in |field.server_predictions()|. This function
-  // chooses relevant for Password Manager predictions.
+  // The main server predictions is in `field.server_type()` but the server can
+  // send additional predictions in `field.server_predictions()`. This function
+  // chooses relevant for Password Manager predictions. Choosing additional
+  // predictions from `field.server_predictions()` is gated on the
+  // `kSecondaryServerFieldPredictions` flag. This is because the server only
+  // recently started to send down these predictions (http://cl/340884706).
+  // Having a feature flag here allows us to run experiments to measure the
+  // impact of these new predictions.
 
   // 1. If there is cvc prediction returns it.
   for (const auto& predictions : field.server_predictions()) {
-    if (predictions.type() == autofill::CREDIT_CARD_VERIFICATION_CODE)
-      return ServerFieldType(predictions.type());
+    if (predictions.type() == autofill::CREDIT_CARD_VERIFICATION_CODE &&
+        AreSecondaryPredictionsEnabled()) {
+      return autofill::CREDIT_CARD_VERIFICATION_CODE;
+    }
   }
 
   // 2. If there is password related prediction returns it.
   for (const auto& predictions : field.server_predictions()) {
-    ServerFieldType type = ServerFieldType(predictions.type());
-    if (DeriveFromServerFieldType(type) != CredentialFieldType::kNone)
+    auto type = static_cast<ServerFieldType>(predictions.type());
+    if (DeriveFromServerFieldType(type) != CredentialFieldType::kNone &&
+        AreSecondaryPredictionsEnabled()) {
       return type;
+    }
   }
 
   // 3. Returns the main prediction.

components/password_manager/core/browser/form_parsing/password_field_prediction_unittest.cc

@@ -8,9 +8,11 @@
 
 #include "base/stl_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/test/scoped_feature_list.h"
 #include "components/autofill/core/browser/form_structure.h"
 #include "components/autofill/core/common/form_data.h"
 #include "components/autofill/core/common/renderer_id.h"
+#include "components/password_manager/core/common/password_manager_features.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -39,7 +41,23 @@ namespace password_manager {
 
 namespace {
 
-TEST(FormPredictionsTest, ConvertToFormPredictions) {
+// The boolean parameter determines the feature state of
+// `kSecondaryServerFieldPredictions`.
+class FormPredictionsTest : public ::testing::TestWithParam<bool> {
+ public:
+  FormPredictionsTest() {
+    feature_list_.InitWithFeatureState(
+        features::kSecondaryServerFieldPredictions,
+        AreSecondaryPredictionsEnabled());
+  }
+
+  bool AreSecondaryPredictionsEnabled() const { return GetParam(); }
+
+ private:
+  base::test::ScopedFeatureList feature_list_;
+};
+
+TEST_P(FormPredictionsTest, ConvertToFormPredictions) {
   struct TestField {
     std::string name;
     std::string form_control_type;
@@ -55,13 +73,20 @@ TEST(FormPredictionsTest, ConvertToFormPredictions) {
       {"Password", "password", PASSWORD, PASSWORD, false},
       {"confirm_password", "password", CONFIRMATION_PASSWORD,
        CONFIRMATION_PASSWORD, true},
-      // username in |additional_types| takes precedence.
-      {"email", "text", EMAIL_ADDRESS, USERNAME, false, {USERNAME}},
-      // cvc in |additional_types| takes precedence.
+      // username in |additional_types| takes precedence if the feature is
+      // enabled.
+      {"email",
+       "text",
+       EMAIL_ADDRESS,
+       AreSecondaryPredictionsEnabled() ? USERNAME : EMAIL_ADDRESS,
+       false,
+       {USERNAME}},
+      // cvc in |additional_types| takes precedence if the feature is enabled.
       {"cvc",
        "password",
        PASSWORD,
-       CREDIT_CARD_VERIFICATION_CODE,
+       AreSecondaryPredictionsEnabled() ? CREDIT_CARD_VERIFICATION_CODE
+                                        : PASSWORD,
        false,
        {CREDIT_CARD_VERIFICATION_CODE}},
       // non-password, non-cvc types in |additional_types| are ignored.
@@ -206,7 +231,7 @@ TEST(FormPredictionsTest, DeriveFromServerFieldType) {
               DeriveFromServerFieldType(test_case.server_type));
   }
 }
-
+INSTANTIATE_TEST_SUITE_P(All, FormPredictionsTest, testing::Bool());
 }  // namespace
 
 }  // namespace password_manager

components/password_manager/core/common/password_manager_features.cc

@@ -84,6 +84,10 @@ const base::Feature kPasswordsWeaknessCheck = {
 const base::Feature kRecoverFromNeverSaveAndroid = {
     "RecoverFromNeverSaveAndroid", base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Enables considering secondary server field predictions during form parsing.
+const base::Feature kSecondaryServerFieldPredictions = {
+    "SecondaryServerFieldPredictions", base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Treat heuritistics to find new password fields as reliable. This enables
 // password generation on more forms, but could lead to false positives.
 const base::Feature kTreatNewPasswordHeuristicsAsReliable = {

components/password_manager/core/common/password_manager_features.h

@@ -33,6 +33,7 @@ extern const base::Feature kPasswordImport;
 extern const base::Feature kPasswordScriptsFetching;
 extern const base::Feature kPasswordsWeaknessCheck;
 extern const base::Feature kRecoverFromNeverSaveAndroid;
+extern const base::Feature kSecondaryServerFieldPredictions;
 extern const base::Feature kTreatNewPasswordHeuristicsAsReliable;
 extern const base::Feature kUsernameFirstFlow;
 extern const base::Feature kWellKnownChangePassword;